Electronic timepiece with calendar device

ABSTRACT

An electronic timepiece has a calendar advancement device resistant to external shock and capable of achieving date correction in a short time. A date dial advancement transducer ( 51 ) is activated in response to a date dial drive signal generated by a 24-hour switch. A date advancement mechanism (a date gear train) ( 52 ) employs a Geneva wheel for stabilizing the date dial ( 70 ). A bounding restraint lever is regulated using an eccentric cam or the like provided coaxially with the Geneva wheel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electronic timepiece having acalendar device which uses a rotating date indication panel or a datedial.

2. Description of the Related Art

In common calendar systems for a conventional wrist watch with acalendar, a date dial is driven by a date dial driving wheel which makesone complete rotation every twenty-four hours, and which constitutes aknown date drive gear train interlocked with a time indication geartrain. Therefore, changing date indication may require about two hoursof advancement time.

It has also conventionally been proposed that an analog indication watchemploys a Geneva mechanism for advancement and stabilization of a datedial. In one technique proposed, for example, in Japanese PatentPublication No. Hei 6-27880, a Geneva wheel is provided, which iscontinuously driven by a continuously driven hand gear train, so as tointermittently rotate a date dial driving wheel for advancing a datedial.

According to this proposal, however, the Geneva wheel, the rotation ofwhich is based on the rotation velocity of the hand gear train, rotatesonly at a slow speed. Therefore, as much as ten to twenty minutes arerequired to fully advance the date dial. As a result, rotation restraintapplied to the date dial driving wheel by the flange of the Geneva wheelmay fail, causing improper movement of the date dial when external shockis applied to the timepiece during such a large amount of time foradvancement, during which the date dial driving wheel is driven by thefeed tooth of the Geneva wheel.

Meanwhile, positioning for conventional rotation restraint imposed onthe date dial has been achieved using a bounding restraint lever. Thedate dial is pressed with a larger force as it is driven for date changeuntil the force peaks when a tooth of the gear of the date dial passesover the apex of a convex of the bounding restraint lever.

In a method for driving a date dial by using a date dial driving wheel,which is rotated by a date drive gear train, date change can besuccessfully achieved irrespective of variation of the pressing forceonto the date dial by the bounding restraint lever because the rotationtorque of the date dial driving wheel is sufficiently large.

In either case, however, too much time is required to change dates andthe period of no-date indication between adjacent date indications,during which the present date indication cannot be easily read, remainstoo long.

In order to solve the above problems, various proposals have been madeto reduce a date dial advancement time to facilitate date indicationreading. One proposal is such that a date advancement nail, whichconstitutes a date dial driving wheel making one complete rotation fortwenty-four hours, is instantly activated so that the date dial isadvanced instantly. Such a date dial driving wheel, however, hasproblems including complicated structure, increased cost, and thickmovements resulting from a required large cross sectional arrangementsize for a date dial driving wheel, a date dial, and associated members.

Another proposal is such that, in a conventional calendar mechanismhaving a date dial driving wheel, which makes one complete rotation fortwenty-hour hours, an indication wheel (a date dial) is driven using adate advancement transducer (a date step motor) dedicated to drive thedate dial (an indication wheel), an electronic circuit fordrive-controlling the date step motor, a gear train, and a drive wheel.

Specifically, in a preferred embodiment disclosed in Japanese UtilityLaid-open No. Hei 4-124494, a step motor is driven in response to adrive pulse from an electronic circuit to transmit rotation via a geartrain to a drive wheel to drive an indication wheel. Also, under controlby the electronic circuit, a pulse in an opposite direction from that ofthe drive pulse is output when completing the drive so that right andleft backlash of the drive and indication wheels is equalized. With thisarrangement, date dial advancement time is reduced and the dateindication can be read more easily.

However, a calendar mechanism in which respective members of a date stepmotor, in particular, a series of components from a rotor to a datedial, constitute a slowdown gear train, has the following problems.

That is, since the date dial is kept positioned utilizing magneticretention of a rotor which constitutes a date step motor, the date dialmay be displaced from its stationary stabilized position when itreceives external disturbance (including shock due to a swinging arm)and thereby generates inertial force resulting in rotating the rotor viathe interlocked slowdown gear train.

Also, date indication may move off a date window (not shown) formed on adial plate when the date dial is caused to rotate due to appliedexternal disturbance by an amount equivalent to the sum of meshingbacklash caused in the respective members of the slowdown gear train,i.e., those from the date dial to the rotor.

SUMMARY OF THE INVENTION

The present invention has been conceived to overcome the above problemsand aims to provide an electronic timepiece having a calendaradvancement device capable of correcting a date dial in a short time,and resistant to external shock.

In order to achieve the above objects, according to one aspect of thepresent invention, there is provided an electronic timepiece having adate dial as a rotating indication panel for dates on a calendar,comprising: a calendar advancement device, including a 24-hour switchfor generating a date dial drive signal for every twenty-four hours; adate dial advancement transducer activated by a control circuit havingreceived the date dial drive signal; and a date advancement mechanismhaving a date dial stabilizing Geneva wheel, and a date dial drivingwheel for engagement with a flange of the Geneva wheel and a date wheelgear of the date dial, and being activated with force from the date dialadvancement transducer.

With the above arrangement, the Geneva wheel is rotated quickly by thedate dial advancement transducer to update dates so that a date changetime and chance for erroneous operation of the date dial due to externalshock can be reduced.

Also, the above electronic time piece may further comprise a detectionmechanism for detecting start to advance the date dial; a countercircuit for counting for a predetermined amount of time in response to asignal from the detection mechanism; and a control circuit forsuspending the date dial advancement transducer based on an output fromthe counter circuit to thereby suspend rotation of the date dialstabilizing Geneva wheel.

With the above arrangement, a constant stop position for the Genevawheel can be achieved using the counter circuit. This can ensurestabilization of the date dial.

Further, in the above electronic timepiece, a feed tooth of the datedial stabilizing Geneva wheel may be located in a region opposite fromthe date dial driving wheel when the date dial is in a stabilized state.

With the above arrangement, the date dial can be further stabilized, andmovement of the date dial in forward or backward direction can behandled in a similar manner.

Still further, the above electronic timepiece may further comprise acontrol circuit for fast-forward-rotating the date dial advancementtransducer during a period from activation of the date dial advancementtransducer to at least abutment of a feed tooth of the date dialstabilizing Geneva wheel on teeth of the date dial driving wheel.

With the above arrangement, time without load can be reduced so that adate change time can be further reduced. Also, movement of the date dialcan be easily assured when the transducer is not rotated quickly.

Still further, the above electronic timepiece may further comprise acontrol circuit for fast-forward-rotating the date dial advancementtransducer for correction of the calendar during a period fromactivation to stoppage of the date dial advancement transducer.

With the above arrangement, correction can be more quickly achieved.

Still further, it is possible to configure the above electronictimepiece so that abutment of the feed tooth of the date dialstabilizing Geneva wheel on the teeth of the date dial driving wheel isjudged from a number counted by the counter circuit.

With the above arrangement, the need for any special abutment detectionmechanism other than a counter circuit can be eliminated.

Still further, in the above electronic timepiece, abutment of the feedtooth of the date dial stabilizing Geneva wheel on the teeth of the datedial driving wheel may be detected from a signal from a detectionmechanism for detecting start to advance the date dial.

With the above arrangement, operation can be carried out at reliabletiming.

Still further, in the above electronic timepiece, the detectionmechanism for detecting start to advance the date dial may have apattern provided on the date dial and a photo sensor for detecting thepattern.

With the above arrangement, there is provided a prompt and sensitivedetection mechanism.

Still further, in the above electronic timepiece, the detectionmechanism for detecting start to advance the date dial may have a loaddetection circuit for detecting load on a drive circuit for the datedial advancement transducer.

With the above, a simpler structure can be achieved.

It is also possible to configure the above electronic timepiece suchthat the feed tooth of the date dial stabilizing Geneva wheel is held ina position, when the date dial is in a stabilized state, which isdetermined according to a ratio between forward and backward rotationspeeds of the date dial advancement transducer so that the correcting ofthe date dial starts after a substantially same amount of time througheither forward or backward rotation.

With the above arrangement, movement of the date dial can be correctedin the same time period through forward or backward rotation.

According to another aspect of the present invention, there is providedan electronic timepiece having a date dial as a rotating indicationpanel for dates on a calendar, comprising: a control device for dates ona calendar, including a date advancement transducer for driving a datedial; a slow-down gear train for transmitting rotation force of the dateadvancement transducer to the date dial; a date dial intermittentrotation drive device constituting a part of the slow-down gear train,for intermittently driving the date dial; and a bounding restraint leverfor restraining rotation of the date dial in a non-driven state, andreleasing rotation restraint on the date dial in a driven state.

With the above arrangement, date dial correction can be achieved in ashort time, and the timepiece is more resistant to shock.

Also, in the above electronic timepiece, the bounding restraint levermay be engaged with teeth of the date dial in a non-driven state forrotation restraint, and departs from the teeth of the date dial in adriven state for releasing load due to pressing force applied to thedate dial.

With the above arrangement, the timepiece is highly resistant to shock.

Further, the above electronic timepiece may be configured such that thedate dial intermittent rotation device includes a date dial drivingwheel arranged for engagement with the date dial all the time, a dateintermediate wheel having feed teeth for intermittent engagement withthe date dial driving wheel, and an eccentric cum for engagement withand rotating the bounding restraint lever, the date intermediate wheeland the eccentric cum having a common rotation center.

With the above arrangement, the bounding restraint lever can be reliablyrotated.

Still further, in the above electronic timepiece, a bearing is providebetween the eccentric cum and the feed teeth, for receiving an axis ofthe date intermediate wheel, and, the bounding restraint lever, theeccentric cum, the teeth of the date dial for engagement with the datedial driving wheel are provided on a same plane surface.

With the above, reduction of a correction time for the date dial, and athin shock-resistive mechanism can be achieved.

According to the above described aspect of the present invention, thedate dial is held still a under consistent stabilized condition when itis in a non-driven state (a normal operation) because the date boundingcontrolling part constrains rotation of the date dial. On the otherhand, when the date dial is in a driven state (date change) only a smallrotation load torque due to the date dial is applied to the step motorbecause the date dial is rotated after rotation restraint applied by thedate bounding restraint part to the date dial is lifted. In this way, anelectronic timepiece with a calendar in stabilized operation conditionis provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the presentinvention will become further apparent from the following description ofthe preferred embodiment taken in conjunction with the accompanyingdrawings wherein:

FIG. 1 is a conceptual diagram relative to an electric timepiece havinga calendar advancement device according to the present invention;

FIG. 2 is a block diagram showing a circuitry structure of theelectronic timepiece shown in FIG. 1;

FIG. 3 is a conceptual diagram showing a detection pattern of anelectronic timepiece according to the present invention;

FIG. 4 is a circuitry diagram showing a photo sensor mechanism for usein an electronic timepiece according to the present invention;

FIG. 5 is a diagram showing waveforms of signals generated by a circuitof the electronic timepiece shown in FIG. 2;

FIG. 6 is a diagram showing partial positional relationship amongmovements of the electronic timepiece shown in FIGS. 1 and 2 of thepresent invention viewed from the above of the timepiece;

FIG. 7 is a diagram showing partial positional relationship amongmovements of a timepiece, corresponding to FIG. 6, viewed from the belowof the timepiece, different from FIG. 6;

FIGS. 8a and 8 b provide a cross sectional diagram of the movement of atimepiece along the date dial advancement transducer, the date geartrain, and the date dial shown in FIG. 6, the drawing being showndivided into two pieces for convenience along the line A—A;

FIG. 9 is an enlarged diagram showing a Geneva wheel and its surroundingmembers viewed from the below of a timepiece for explaining positionalrelationship among the respective members;

FIG. 10 is a diagram for explaining play in the rotation direction ofthe date dial and variation of pressing force applied by the datebounding restraint part to the teeth of the date dial during a periodwhen the date intermediate wheel makes one complete rotation, the playbeing caused resulting from rotation of the date dial intermittentrotation drive device, such as a Geneva wheel;

FIG. 11 is a block diagram showing circuitry structure, corresponding toFIG. 2, of another preferred embodiment of the present invention;

FIG. 12 is a diagram showing waveforms of signals generated by a circuithaving the structure shown in FIG. 11;

FIG. 13 is a block diagram showing a circuitry structure, correspondingto FIG. 2, of still another preferred embodiment of the presentinvention;

FIG. 14 is a diagram showing waveforms of signals generated by a circuithaving the structure shown in FIG. 13;

FIG. 15 is a block diagram showing a circuitry structure, correspondingto FIG. 13, of still another preferred embodiment of the presentinvention;

FIG. 16 is a block diagram showing a circuitry structure, correspondingto FIGS. 13 and 15, of still another preferred embodiment of the presentinvention; and

FIG. 17 is a block diagram showing a circuitry structure, correspondingto FIG. 2, of yet another preferred embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram showing a structure of an electronictimepiece having a calendar advancement device according to the presentinvention. FIG. 2 is a block diagram showing a circuitry structure ofthe electronic timepiece shown in FIG. 1. In these drawings, a signalfrom an oscillation circuit 2 for oscillating a quartz oscillator 1 isdivided into 1 Hz in the divide circuit 3, and the waveform thereof isadjusted in a waveform adjustment circuit (1) 4 (not shown in FIG. 1)before the signal is supplied to a drive circuit (1) 5 for driving atransducer (1) 6, which comprises a step motor in this embodiment. Inresponse to a signal from the drive circuit (1) 5, the transducer (1) 6is driven every second. Rotation force generated by the transducer (1) 6is transmitted to a hand gear train 7, rotating a second hand 8 and aminute hand 9. Further, an hour gear train 7 a, which is a part of thehand gear train, rotates an hour hand 10 and further a switchwheel 11,which makes one complete rotation for twenty-four hours, to turn on an24-hour switch 12 every twenty-four hours.

The 24-hour switch 12 outputs a date dial drive signal 24SW for drivingthe date dial 70 to a control circuit 20.

In response to the signal 24SW, the control circuit 20 supplies acommand signal (a date dial drive signal) BMC for driving the date dial70 to a waveform adjustment circuit (2) 13 (not shown in FIG. 1). Thewaveform adjustment circuit (2) 13, which also receives a signal fromthe divide circuit 3, adjusts waveform of a signal from the dividecircuit 3 based on the date dial drive signal BMC, and outputs aresultant signal as a drive signal MOTB to a drive circuit (2) 50. Thedrive circuit (2) 50 then drives a transducer (2) 51, which comprises astep motor in this embodiment. The transducer (2) 51 drives a date geartrain 52, which in turn drives the date dial 70. In this embodiment, thedate gear train 52 constitutes a date advancement mechanism.

Besides a date dial drive signal BMC, the control signal 20 outputs adrive signal LD to a photo sensor mechanism 80.

The photo sensor mechanism 80 comprises a photo sensor 81 and adetection circuit 82, the former including a light emitter 81 a and alight receiver 81 b.

The date dial 70 has a detection pattern 71, which includes a reflectivepart and a non-reflective part, printed on the rear surface thereof, andis used in detection of the start of advancing the date dial 70. Thephoto sensor mechanism 80 reads a boundary in the detection pattern 71according to the movement of the date dial 70, and outputs a detectionsignal SD to the counter circuit 90.

In response to the detection signal SD, the counter circuit 90 beginscounting a drive signal MOTB, and, after having counted for apredetermined time, supplies a count up signal CUP to the controlcircuit 20. In response to the count up signal CUP, the circuit 20suspends output of a date dial drive signal BMC.

Referring to FIG. 1, a hand correction gear train 100 and a timedifference correction gear train 120 are connected to an hour gear train7 a. The drawing also schematically shows a winding crown 130 set inzero, first, and second stage positions by a setting mechanism 135 sothat a signal corresponding to each position is accordingly sent to aswitch control circuit 45.

One preferred embodiment of a detection pattern 71 will next bedescribed referring to FIG. 3.

FIG. 3 is a conceptual diagram showing a detection pattern on the rearsurface of a date dial, in which a black part is a non-reflective part71 a, a white part is a reflective part 71 b, and n and n+1 lines definean interval for one-day date indication.

When the data panel 70 is in a stabilized state (a normal state), thedate dial 70 is positioned such that the middle part (indicated by thedotted line) of the n or n+1 line of the detection pattern 71 ispositioned under the center of the detector of the photo sensor 81.Non-reflective parts, corresponding to the n or n+1 line, for thirty-onedays are provided on the date dial 70. In the drawing, the arrow Cindicates the rotation direction.

Referring to the middle left of FIG. 1, positional relationship betweenthe detection pattern 71 on the rear surface of the date dial 70 and thephoto sensor 81 is conceptually shown.

FIG. 4 is a diagram showing an internal circuit of a photo sensormechanism 80, which comprises a photo sensor 81 and a detection circuit82.

In response to a signal 24SW from the 24-hour switch 12, the controlcircuit 20 drives, via a drive signal LD for the photo sensor mechanism80, FETs 82 a, 82 b of the detection circuit 82. Then, electric currentflows from the level VDD through the light emitter 81 a of the photosensor 81 and the resistance 82 c to the level VSS, whereby light B isemitted. When the light B is reflected on the rear surface of the datedial 70, the reflected light reaches and thereby activates the lightreceiver 81 b. Thereupon, electric current flows from the level VDDthrough a detection resistance 82 d and FET 82 b to the level vss, sothat an H-level signal PH is supplied via the detection resistance 82 dto a comparator 82 e. After inversion in an inverter 82 f, the detectioncircuit 82 outputs the signal as an L-level detection signal SD. On theother hand, in the case where the light 8 irradiates a non-reflectivepart on the date dial 70, and thus is not reflected, the light receiver81 b is not activated. Therefore, an H-level detection signal SD isoutput.

FIG. 5 is a diagram showing waveforms of the signals generated by thecircuit of an electric timepiece shown in FIG. 2.

When a date dial drive signal 24SW becomes H level, a date dial drivesignal BMC from the control circuit 20 also becomes H level.

Then, the waveform adjustment circuit (2) 13 outputs a drive signal MOTBfor driving the transducer (2) 51, upon which the transducer (2) 51begins rotating, thereby rotating the date gear train 52.

As the date dial 70 accordingly begins rotating, the detector of thephoto sensor 81 of the photo sensor mechanism 80 resultantly moves froma non-reflective part to a reflective part of the detection pattern 71on the date dial 70, as a result of which an L-level detection signal SDis output.

With an L-level detection signal SD is output, the counter circuit 90begins counting drive signals MOTB. Having counted a predeterminednumber of signals MOTB, the counter circuit 90 outputs a count up signalCUP, in response to which the date dial drive signal BMC becomesL-level. As a non-reflective part of the detection pattern 71 (e.g., then+1 part shown in FIG. 3) is then positioned below the photo sensor 81when the date dial 70 stops rotating, a detection signal SD becomesH-level.

Next, positional relationship among the transducer (2) 51, the date geartrain 52 as a date advancement mechanism, and a date dial 70 will bedescribed.

FIG. 6 is a diagram showing partial positional relationship amongmovements of a timepiece viewed from the above (the rear side surface).

In the following, a mechanical structure and operation of the abovedescribed preferred embodiment will be described in detail.

FIG. 7 is a diagram showing partial positional relationship amongtimepiece movements, in particular, a part of a date advancementtransducer (a date step motor) and a date gear train (a date drive geartrain) viewed from the below of the timepiece, different from FIG. 6. Inthe drawing, respective movements are shown displaced from one anotherfor convenience in explanation of their arrangement.

Also, components of a date intermediate wheel (3) 55 and a date dialdriving wheel 57 are shown separated for easy understanding of the driveforce transmission path for the date intermediate wheel (3) 55, the datedial driving wheel 57, an eccentric cam 55 b, and the date dial 70. Thatis, the arrow of a dotted line drawn from the date intermediate wheel(3) 55 to the eccentric cam 55 b, and that from the intermediate datewheel gear 57 a to the date dial driving wheel gear 57 b represent driveforce transmission paths. Drive force is transmitted by the eccentriccam 55 b and the date intermediate wheel axis 55 c together making onecomplete rotation, and the date dial driving wheel gear 57 b and theintermediate date wheel gear 57 a together making one complete rotation.

FIG. 8 is a cross sectional view along the transducer (2) 51, the dategear train 52, and the date dial 70 shown in FIG. 6, the view beingdivided in two pieces for convenience along the dotted line A—A.

Referring to FIGS. 6 through 8, the date rotor 51 c and the date geartrain 52 are basically held on the base plate 200 and a gear trainbridge 150. The date coil 51 a and the date stator 51 b of thetransducer (2) 51 are held via a screw (not shown) on the base plate200.

The date dial driving wheel 57 is held on a pin 152 a formed on ancenter wheel cock 152, and abutted by the date dial guard 151 on oneside.

Note that the drawing also shows a circuit substrate 210, a circuitsupport plate 212, a dial plate 213, and a dial plate receiving ring214.

A date intermediate wheel axis 55 c, a part of the date intermediatewheel (3) 55, pierces the center wheel cock 152, with lower and uppertenons thereof being axially held by the bearing and by the bearing ofthe gear train bridge 150, respectively. Below the lower surface of thecenter wheel cock 152, a middle shoulder part is provided having amaximum diameter and a two-face-cut part formed on the externalcircumference thereof.

Below the middle shoulder part, a date intermediate wheel gear 55 a ispress-fit for receiving rotation force of the date intermediate wheel(2) 54, and a Geneva wheel 56 is press-fit below the wheel gear 55 a.The lower axial portion below the lower tenon of the date intermediatewheel axis 55 c, which projects towards the dial plate 213 side, has atwo-face-cut part 55 d formed thereon to be engaged with a D-cut hole ofthe eccentric cam 55 b for receiving rotation force.

As the eccentric cam is engaged with the axial tip of the lower tenon ofthe date intermediate wheel axis 55 c, which is axially held by the geartrain bridge and the bearing of the base plate, there can be provided astable date dial control mechanism which is less affected by thepressing force applied by the bounding restraint lever which restrainsrotation of the date dial. (For example, reaction of the pressing forceapplied by the bounding restraint lever to date dial, which is engagedwith the lever via the teeth thereof, may act as a couple force on thebearing of the date intermediate wheel gear via the eccentric cam,increasing friction on the bearing and affecting rotation force of thedate step motor which drives the date intermediate wheel (3) 55.)

The two-face-cut part on the part having the largest diameter of thedate intermediate wheel axis 55 c is formed in the same direction asthat for the two-face-cut part formed on the lower axial part of thedate intermediate wheel axis 55 c. Therefore, for assembling the dateintermediate nail (Geneva wheel) 56 to the date intermediate wheel axis55 c through press-fitting, the two-face-cut part on the largestdiameter part of the wheel axis 55 c is initially positioned by using atool such that the two-face-cut part on the lower axial part issubstantially matched with the feed tooth (finger part) 56 b so that theGeneva wheel 56 is assembled such that the finger part 56 b thereof canbe easily set accordingly. With this arrangement, the finger part 56 bcan be positioned substantially matched with the eccentric cam 55 b forsynchronizing operation of the date dial intermittent rotation drivedevice and the bounding restraint lever 58, and the date dial 70 can beset free from the pressing force applied by the date boundingcontrolling part 58 b when the date dial 70 is driven. Further, aneyehole 200 d (see FIG. 7) is formed on the base plate 20, through whichthe position of the finger part 56 b can be assured when assembling theeccentric cam 55 b from the dial plate 213 side into the two-face-cutpart on the lower axis in accordance with the position of the fingerpart 56 b. With provision of the eyehole 200 d, error assembly of theeccentric cam 55 b can be avoided. (The eccentric cam 55 b can beassembled in two different plane positions, and, with an erroneouslyassembled eccentric cam 55 b, pressing force applied to the driven datedial 70 by the bounding restraint part 58 b could not be released.)

A center wheel cock 152 is provided in a cross sectional hollow part inthe base plate 200 and the gear train bridge 150, for axially supportingother gear train mechanisms (not shown), and a date dial driving wheelaxis 152 a is formed on the center wheel cock 152. The date dial drivingwheel 57 is assembled from the dial plate 213 side such that its surfaceon the intermediate date wheel gear 57 a side faces the date dialdriving wheel axis 152 b, and is pressed and held by the date dial guard151 on its side, i.e., the side with the date dial driving wheel gear 57b of the date dial driving wheel 57.

An engagement position between the date dial driving wheel gear 57 b andthe teeth 70 a of the date dial 70, the eccentric cam 55 b, and thebounding restraint lever 58 are arranged within a space equivalent tothe thickness of the thin rear plate 216, which is provided in thehollow parts in the base plate 200 and the date dial guard 151.

Winding stem spacers 211 are provided on the upper surface of the datestator 51 b and the date intermediate wheel (3) 55, and in a crosssectional hollow part in the base plate 200 and the center wheel cock152, and a guide hole 211 a is formed on the winding stem spacer 211,for preventing falling down of these members when assembling.

When the 24-hour switch 12 is switched on, the control circuit 20outputs a drive signal BMC for the transducer (2) 51, in response towhich the drive circuit (2) 50 drives the transducer (2) 51. Thetransducer (2) 51 is a step motor which comprises a date coil 51 a, adate stator 51 b, and a date rotor 51 c in this embodiment. Rotation ofthe date rotor 51 c is transmitted, while being decelerated, to the dateintermediate wheels (1) 53, (2) 54, (3) 55. The date intermediate wheel(3) 55 comprises a gear 55 a and a Geneva wheel 56, which are fixedlyformed integrated with the date intermediate wheel axis 55 c, the Genevawheel 56 including the flange 56 a and a feed tooth (date intermediatenail) 56 b. Engaged with the date intermediate wheel axis 55 c of thedate intermediate wheel (3) 55 on the side other than that with the dateintermediate nail 56, i.e., the Geneva wheel 56 here, with respect tothe base plate 200 is an eccentric cam 55 b. The D-cut part of the dateintermediate wheel axis 55 c is fit into the D-cut hole on the eccentriccam 55 b.

Generally, the Geneva wheel 56 makes one complete rotation every day,with rotation force applied by the transducer (2) 51 via the feed tooththereof the intermediate date wheel gear 57 a of the date dial drivingwheel 57 so that the date dial driving wheel gear 57 b, integrated withthe wheel gear 57 a, can advance the date wheel gear 70 a of the datedial 70 once a day. In general, the Geneva wheel 56 is positioned suchthat the flange 56 a thereof contacts two teeth of the intermediate datewheel gear 57 a so that the date dial driving wheel 57 is blocked fromrotating. A date gear train 52 here is the gear train consisting therespective members from the date intermediate wheel (1) 53 to the datedial driving wheel 57.

The bounding restraint lever 58 is supported on the base plate 200 withthe bounding restraint lever pin 59 as the rotation center. Theeccentric cam 55 b, engaged with a fork part 58 e, or a cut-in part, ofthe bounding restraint lever working part 58 a of the bounding restraintlever 58, serves to change deflection of the bounding restraint spring58 c, which supports the date bounding restraint part 58 b meshed withthe date wheel gear 70 a, and moves the date bounding restraint part 58b away from the date wheel gear 70 a. Extended parts of the datebounding restraint part 58 b and the rigid part 58 d are formed by-meansof shirring, and cut apart. The bounding restraint lever 58 is formedsuch that the date bounding restraint part 58 b is integrated with thebounding restraint spring 58 c. While the feed tooth 56 b advances thedate dial driving wheel 57, the deflection of the bounding restraintspring 58 b is kept small or the date bounding restraint part 58 b iskept away from the date wheel gear 70 a so as to maintain small energyfor advancing the date dial 70. The bounding restraint lever 58 ispositioned as indicated by the dot line in FIG. 7 when advancing thedate dial 70.

When the date dial 70 is in a non-driven state in normal operation, thebounding restraint lever 58 is positioned as indicated by the solid linein FIG. 7. The cut-apart part of the date bounding restraint part 58 bis then open with the bounding restraint spring 58 c being elasticallydeformed. On the other hand, when the date dial 70 is driven around 0o'clock midnight for date change, the bounding restraint lever 58 is ina position indicated by the two-dot and dash line in FIG. 7, with thecut-apart part being closed as it is formed through shirring.

As described above, the transducer (2) 51 is activated for every turningof the 24-hour switch 12, and the date gear train 52 advances the datedial 70 for one day.

Note that the rotating plate for date indication, or the date dial 70,is a thin ring plate with dates from 1 to 31 printed on its surface.Along the inside circumference of the date dial 70, 62 teeth 70 b (twoteeth for one-day advancement) are formed in an integrated manner.

In normal operation (at times other than date change), the intermediatedate wheel gear 57 a is engaged via two teeth thereof with the sidesurface of the flange 56 a of the Geneva wheel 56 for rotationrestraint, and the date dial 70 is engaged via one tooth of the datewheel gear 70 a thereof with two teeth of the date dial driving wheelgear 57 b for rotation restraint.

During date change, the feed tooth 56 b and one of the two shoulders ofthe Geneva wheel 56 together advance the intermediate date wheel gear 57b by two teeth, thereby rotating the data panel 70 by two teeth.

The eccentric cam 55 b has a D-cut part, or the round hole for arotation center cut to have two line edges, and the D-cut hole receivesthe D-cut part of the date intermediate wheel axis 55 c.

FIG. 9 is a diagram for explaining arrangement of the Geneva wheel 56,the bounding restraint lever 58, the date dial driving wheel 57, and thedate dial 70, and operation of the Geneva wheel 56. The drawing shows apart of the members shown in FIGS. 6 and 7, viewed from the bottom (thedial side) of a timepiece, different from FIG. 6 and similar to FIG. 7,in which identical members to those shown in FIGS. 6 and 7 are givenidentical reference numerals.

The Geneva wheel 56 is indicated by the dotted line. Reference Jindicates a stop position where the feed tooth 56 b of the Geneva wheel56 is generally positioned when the Geneva wheel 56 stops rotating, inother words, until the transducer (2) 51 is driven in response to asignal 24SW from the 24-hour switch 12. When the date rotor 51 c of thetransducer (2) 51 begins rotating, the Geneva wheel 56, a part of thedate gear train 52, begins rotating in the direction of the arrow D(forward direction) until the feed tooth 56 b thereof arrives at theposition K. With the feed tooth 56 b in the position K, the teeth of theintermediate date wheel gear 57 a are disengaged with the flange 56 a ofthe Geneva wheel 56, upon which the date dial driving wheel 57 enters anadvancement state. Meanwhile, the eccentric cam 55 b, engaged with thedate intermediate wheel axis 55 c of the date intermediate wheel (3) 55,also begins rotating, and the bounding restraint lever 58 is therebyrotated around the bounding restraint lever pin 59, reducing thepressing force applied by the date bouncing restraint part 58 b to thedate gear wheel 70 a. Thereafter, the feed tooth 56 b of the Genevawheel 56 abuts on the teeth of the intermediate date wheel gear 57 a ofthe data rotation wheel 57, advancing the date dial driving wheel 57 inthe direction with the arrow E. As the date dial driving wheel gear 57 bof the date dial driving wheel 57 drives the date wheel gear 70 a, thedate dial 70 also begins rotating in the arrow F. Meanwhile, the datebounding restraint part 58 b of the bounding restraint lever 58temporarily departs from the date wheel gear 70 a. At the beginning ofadvancing the date dial 70, the photo sensor mechanism 80 detects thedetection pattern 71 on the rear surface of the date dial 70, and thenoutputs a detection signal SD. In response to the detection signal SD,the counter circuit 90 begins counting a drive signal MOTB.

The feed tooth 56 b advances the intermediate date wheel gear 57 a bytwo teeth and, as a consequence, also the date wheel gear 70 a by twoteeth. As a result, the date dial 70 has been advanced for one day.Thereafter, the date bounding restraint part 58 b of the boundingrestraint lever 58 is re-engaged with the date wheel gear 70 a torestrain bounding of the date wheel gear 70 a. When the feed tooth 56 bhas arrived at the position L, advancing the date dial 70 is completed.

The Geneva wheel 56 continues rotating until the counter circuit 90 hasreached a predetermined number, and outputs a count up signal CUP. Inresponse to the count up signal CUP, output of a drive signal BMC issuspended as described above, in response to which the transducer (2) 51suspends operation, and the Geneva wheel 56 also suspend rotation.

By the completion of the above process, the feed tooth 56 b has returnedto the position J, where the Geneva wheel 56 is again in an await state.As the position J is located on the opposite side from the date dialdriving wheel 57, as shown in FIG. 9, a stabilized state of the datedial 70 can be ensured.

When the date dial 70 is rotated backward, i.e., in the direction withthe arrow G, for correction, the Geneva wheel 56 and the date dialdriving wheel 57 rotate in the opposite directions from those with thearrows D and E, respectively, for reverse advancement.

With the date dial 70 in a stabilized state, the feed tooth 56 b remainsin an await position indicated by the dot line M in the drawing, theawait position being determined in consideration of reverse correction.In a transducer using a step motor, a forward advancement speed isgenerally faster than a reverse advancement speed, the ratio of which isoften 2:1. With such a ratio, in order to provide a user-friendlymechanism wherein correction can be started at the same time througheither forward or backward rotation, the feed tooth 56 b is preferablyheld in a position determined according to the ratio between the forwardand backward rotation speeds of the transducer. The position indicatedby the dot line M is a stop position for the feed tooth 56 b in the casethat the ratio between the forward and backward rotation speeds is 2:1.The stop position can be achieved by setting an appropriate number to becounted by the counter circuit 90.

Referring to FIG. 10, relationship between operation of the feed tooth56 b, which drives the date dial driving wheel 57 and the date dial 70for intermitted rotation, and working timing of the bounding restraintlever 58 will be described.

The lateral axis in FIG. 10 corresponds to one complete rotation of thedate intermediate wheel (3) 55. The graph of FIG. 10 shows a play amountin the rotation direction of the date dial and pressing force applied bythe bounding restraint lever which are measured while rotating the dateintermediate wheel (3) 55 by each predetermined amount. The solid lineindicates variation of a play amount accompanying rotation of the datedial intermittent rotation drive device, and the thick broken lineindicates variation of pressing force applied by the date boundingrestraint part 58 b of the bounding restraint lever 58 to the date wheelgear 70 a of the date dial 70.

The term “rotation direction →” in FIG. 10 corresponds to the forwardrotation direction of the date intermediate wheel (3) 55; the point J(see FIG. 9) corresponds to the right and left ends on the lateral axis;and the points K and L correspond to the points P1 and P2 on the solidline, respectively.

When the feed tooth 56 is at the point J, the bounding restraint lever58 applies via the date bounding restraint part 58 b thereof consistentpressing force to the date wheel gear 70 a of the date dial 70.

As the date intermediate wheel (3) 55 in condition corresponding to theleft end of FIG. 10 begins rotating, the eccentric cam 55 b beginsrotating in synchronism therewith, driving the bounding restraint lever58. With the lever 58 being driven, the pressing force applied by thedate bounding restraint part 58 b decreases as depicted in FIG. 10 bythe broken thick line slanting downward to the right, until the datebounding restraint part 58 b departs from the date wheel gear 70 abefore the point P1 (Point J1 in FIG. 10).

By the time the eccentric cam 5Ob has rotated from the normal stopposition J by an amount corresponding to a half rotation by the feedtooth 56 b, the date bounding restraint part 58 b of the boundingrestraint lever 58 will have been moved completely away from therotation locus area of the date wheel gear 70 a of the date dial 70, andthe date dial 70 will have been released from the pressing force. Thebounding restraint lever 58 is positioned as indicated by the two-dotand dash line in FIG. 7 resulting from rotation by a maximum amount.

In the above condition, the date dial 70 is engaged only with the datedial driving wheel gear 57 b, and subjected to rotation restraint (i.e.,in condition where some backlash is caused on the date wheel gear 70 aof the date dial 70 and the date dial driving wheel gear 57 b).

When the rotating date intermediate wheel (3) 55 has rotated passing thepoint P2, the bounding restraint lever 58 comes to be gradually drivenby the rotating eccentric cam 55 b, causing the date bounding restraintpart 58 b to contact again the date wheel gear 70 a of the date dial 70(Point J2 in FIG. 10). Accordingly, pressing force increases as the feedtooth 56 b comes closer to Point J, where the pressing force is fullyrestored, as depicted in FIG. 10 by the broken thick line rising to theright.

When the date dial 70 begins rotating due to rotation of the date dialdriving wheel 57 a caused by the date intermediate wheel (3) 55, nopressing force is applied to the date dial 70 by the date boundingrestraint part 58. Therefore, the transducer (2) (date step motor) 51receives only a small rotation load torque from the rotating date dial70. With the above arrangement, there can be provided a stable datedriving mechanism, similar to a general step motor for hour indication.

Referring to FIGS. 11 and 12, a preferred embodiment of the presentinvention will be described in which load of the drive circuit (2)50 isdetected for starting activation of the counter circuit 90.

FIG. 11 is a block diagram corresponding to FIG. 2 and showing a circuitstructure of an electric timepiece according to the present embodiment,and in which respective elements are given reference numeralscorresponding to those in FIG. 2. The circuit relative to FIG. 11includes a load detection circuit 91 in the place of the photo sensormechanism 80 in FIG. 2.

FIG. 12 shows waveforms of the signals generated by a circuit having thestructure shown in FIG. 9.

In response to a date dial drive signal 24SW from the 24-hour switch 12,the control circuit 121 outputs a date dial drive signal BMC to thewaveform adjustment circuit (2) 13. The waveform adjustment circuit (2)13, also receiving a signal from the divide circuit 3, begins to outputa drive signal MOTB. In response to the drive signal MOTB, the drivecircuit (2) 50 drives the transducer (2) 51, the date gear train 52, andthe date dial 70. As the date dial 70 begins rotating, a larger load isimposed. Variation of the load is detected by the load detection circuit91, which then outputs a load detection signal HD. The load detectioncircuit 91 changes the signal HD from normal H level to L level when theload exceeds a predetermined amount. Based on the change of the loaddetection signal HD, the counter circuit 90 begins counting drivesignals MOTB, and, when it has counted a predetermined number of signalsMOTB, outputs a count up signal CUP to the control circuit 121. Inresponse to the count up signal CUP, the control circuit 121 suspendsoutput of the date dial drive signal BMC, and, as a consequence, outputof the drive signal MOTB is also suspended.

In this embodiment, the stop position for the Geneva wheel can becontrolled through provision of a simply-structured load detectioncircuit 91 in the place of the photo sensor mechanism 80, and thesetting of an appropriate number to the counter circuit 90.

With this arrangement, in which change of the detection patternaccording to the movement of the date dial, and change from mechanicalchange, such as change of load on a drive circuit, are detected so thatthe counter circuit can operate based thereupon, the feed tooth of theGeneva wheel can be properly returned to a temporal stop position andheld there.

A preferred embodiment in which the speed of the transducer (2) 51 ischanged will next be described. This embodiment is based on theunderstanding that load becomes larger only in advancing the date dial70, and remains small when the transducer (2) 51 rotates before andafter the advancement. Referring to FIG. 9, the date dial 70 is not yetrotated during a period from activation of the date dial advancementtransducer (2) 51 to abutment of the feed tooth 56 b of the date dialstabilizing Geneva wheel 56 on the teeth of the intermediate date wheelgear 57 a of the date dial driving wheel 57 b. During this period, theload due to rotation of the date dial 70 is small. Also, when the feedtooth 56 b is disengaged with the teeth of the intermediate date wheelgear 57 a with the date dial 70 having been rotated, that load becomessmall again. FIG. 13 is a block diagram showing the circuitry structureof an electronic timepiece according this preferred embodiment,corresponding to that which is shown in FIG. 2, in which respectiveelements are given reference numerals corresponding to those in FIG. 2.

In the structure shown in FIG. 13, a detection signal SD from the photosensor mechanism 80 is supplied also to the waveform adjustment circuit(3) 213.

FIG. 14 is a diagram showing waveforms of signals generated by thecircuit having the structure shown in FIG. 13.

Referring to FIGS. 13 and 14, in response to a date dial drive signal24SW from the 24-hour switch 12, the control circuit 220 outputs a datedial drive signal BMC to the waveform adjustment circuit (3) 213. Havingreceived a signal from the divide circuit 3, the waveform adjustmentcircuit (3) 213 begins outputting a drive signal MOTB. The drive signalMOTB is output as a fast-forwarding pulse until the date dial 70 beginsrotating due to the drive circuit (2) 50, the transducer (2) 51, and thedate gear train 52. After the date dial 70 begins rotating, a photosensor mechanism 80 detects change of the detection pattern 71 on therear surface of the date dial, and a detection signal SD accordinglybecomes L level. The L-level detection signal is supplied to thewaveform adjustment circuit (3) 213 to switch a drive signal MOTB into aslow-forwarding pulse. Meanwhile, having received a detection signal SD,the counter circuit 90 begins counting a pulse of a signal MOTB.

Thereafter, when advancing of the date dial 70 is completed, and thedetection signal SD from the photo sensor mechanism 80 thereupon becomesH-level, the waveform adjustment circuit (3) 213, receiving an H-leveldetection signal SD, switches the detection signal SD to afast-forwarding pulse. The counter circuit 90 continuously counts thepulse of the drive signal MOTB until it has reached a predeterminednumber. When it has counted that predetermined number, the countercircuit 90 outputs a count up signal CUP, in response to which thecontrol circuit 220 suspends output of a date dial drive signal BMC. Asdescribed above, since a drive signal MOTB is fast-forwarded before andafter advancement of the date dial 70 (rotation of the date dial 70),reduction of a date change time can be achieved without imposing extraload on the drive circuit (2) 50. Also, as the signal is aslow-forwarding pulse while the date dial 70 is rotating, operation foradvancing the date dial can be easily assured.

FIG. 15 is a block diagram showing a circuitry structure according tostill another preferred embodiment, one corresponding to that which isshown in FIG. 13 and in which the respective members are given referencenumerals corresponding to those shown in FIG. 11. In this embodiment, aload detection circuit 391 is provided in the place of the photo sensormechanism, for detecting variation of load imposed on the drive circuit(2) 50.

Signals generated in the circuit having the structure shown in FIG. 15have waveforms as shown in FIG. 12, except that the detection signal SDis replaced by a signal HD. A detection signal HD is shown in FIG. 14.The circuit relative to FIG. 15 operates basically in the same mannerfor the circuit relative to FIGS. 13 and 14.

In response to a signal 24SW from the 24-hour switch 12, the controlcircuit 320 outputs a date dial drive signal BMC to the waveformadjustment circuit (3) 213, which in turn outputs a drive signal MOTB.Larger load is imposed on the drive circuit (2) 50 when the date dial 70is advanced. The increased load is detected by the load detectioncircuit 391 which accordingly changes the detection signal HD fromH-level to L-level. Until the change of the signal level, the signalMOTB is a fast-forwarding pulse, similar to the embodiment of FIG. 13,and thereafter becomes a slow-forwarding pulse.

After the date dial 70 is advanced, the load on the drive circuit (2) 50accordingly becomes smaller again and the detection circuit 391 outputsan H-level detection signal HD, in response to which the drive signalMOTB becomes a fast-forwarding pulse.

As described with reference to FIGS. 13 and 14, the counter circuit 90starts counting the pulses of drive signals MOTB from the moment whenthe detection signal HD has changed from H-level to L-level. When thecounter 90 has reached a predetermined number, it outputs a count upsignal CUP to the control circuit 320 to stop the output of a date dialdrive signal BMC. Also in the embodiment, as a drive signal MOTB isfast-forwarded before and after advancing the date dial 70 (rotation ofthe date dial), reduction of a date change time can be achieved withoutimposing extra load on the drive circuit (2) 59, and operation for dateadvancement can be easily assured.

FIG. 16 is a block diagram showing a circuitry structure of an electrictimepiece according to yet another preferred embodiment corresponding tothose which are shown in FIGS. 13 and 15. In this embodiment, thefunction of the photo sensor 80 in FIG. 13 or the load detection circuit391 and the counter circuit 90 in FIG. 15 is achieved by a countercircuit (2) 190. Respective signals generated in the circuit having thestructure shown in FIG. 16 have waveforms as shown in FIG. 14, exceptthat the counter circuit (2) 190 outputs signals HD and CUP. The countercircuit (2) 190 begins counting the pulses of drive signals MOTB fromthe start of generation of drive signals MOTB (the drive signal MOTBthen being a fast-forwarding pulse). When the counter circuit (2) 190has reached a predetermined number, which is before starting advancementof the date dial, it changes the level of a signal HD from H-level toL-level. Based on the signal with a changed level, the drive signal MOTBis changed to a normal slow-forwarding pulse to be counted. When thepredetermined number of drive signals MOTB have been counted, whichcorresponds to completion of advancing of the date dial, the signal HDbecomes H-level again, and the signal MOTB thereupon becomes afast-forwarding pulse again. Thereafter, the counter circuit (2) 190continues counting a signal MOTB until it has counted a predeterminednumber whereupon it outputs a count-up signal CUP. In response to thecount-up signal CUP, the control circuit 320 suspends output of the datedial drive signal BMC.

In another preferred embodiment of the present invention, the transducer(2) 51 is fast-rotated for correcting a calendar during a period fromactivation to stoppage of the date dial advancement transducer (2) 51.

FIG. 17 is a block diagram showing a circuitry structure of anelectronic timepiece corresponding to that shown in FIG. 2, and in whichidentical components are given identical reference numerals to those inFIG. 2. In this drawing, the waveform adjustment circuit (3) 413, thecontrol circuit 420, and the external operation switch 131 havedifferent structures from those of the corresponding members shown inFIG. 2.

In normal operation, the date dial 70 is updated (advanced) in the samemanner as described above with reference to FIG. 2.

When the external operation switch 131 is turned on by a winding crownor the like for correction, current flows via the resistance 131 a,supplying a H-level signal to the control circuit 420. In response tothe H-level signal, the control circuit 420 outputs a correction signalSC to the waveform adjustment circuit (3) 413. With this arrangement,the waveform adjustment circuit (3) 413 outputs a drive signal MOTB as afast-forwarding pulse during a period when the date dial drive signalBMC is supplied to the waveform adjustment circuit (3) 413. As a result,correction can be promptly achieved.

INDUSTRIAL APPLICATION

As described above, an electronic timepiece having a calendar deviceaccording to the present invention is preferably used in an electronicwrist watch or a small portable timepiece.

What is claimed is:
 1. An electronic timepiece having a date dial as arotating indication panel for dates on a calendar, comprising: acalendar advancement device, including a 24-hour switch for generating adate dial drive signal every twenty-four hours; a date dial advancementtransducer activated by a control circuit having received the date dialdrive signal; and a date advancement mechanism having a date dialstabilizing Geneva wheel, and a date dial driving wheel for engagementwith a flange of the Geneva wheel and a date wheel gear of the datedial, and being activated with force from said date dial advancementtransducer.
 2. An electronic timepiece having a calendar advancementdevice according to claim 1 further comprising: a detection mechanismfor detecting start to advance the date dial; a counter circuit forcounting for a predetermined amount of time in response to a signal fromsaid detection mechanism; and a control circuit for suspending said datedial advancement transducer based on an output from said counter circuitto thereby suspend rotation of the date dial stabilizing Geneva wheel.3. An electronic timepiece having a calendar advancement deviceaccording to claim 1, wherein a feed tooth of the date dial stabilizingGeneva wheel is located in a region opposite from said date dial drivingwheel when the date dial is in a stabilized state.
 4. An electronictimepiece having a calendar advancement device according to any one ofclaims 1, 2 and 3, further comprising a control circuit forfast-forward-rotating said date dial advancement transducer during aperiod from activation of said date dial advancement transducer to atleast abutment of the feed tooth of the date dial stabilizing Genevawheel on teeth of said date dial driving wheel.
 5. An electronictimepiece having a calendar device according to claim 4, whereinabutment of the feed tooth of the date dial stabilizing Geneva wheel onthe teeth of said date dial driving wheel is judged from a numbercounted by said counter circuit.
 6. An electronic timepiece having acalendar device according to claim 2, wherein the detection mechanismfor detecting start to advance the date dial has a pattern provided onthe date dial and a photo sensor for detecting the pattern.
 7. Anelectronic timepiece having a calendar device according to claim 2,wherein the detection mechanism for detecting start to advance the datedial has a load detection circuit for detecting load on a drive circuitfor said date dial advancement transducer.
 8. An electronic timepiecehaving a calendar advancement device according to claim 2, furthercomprising a control circuit for fast-forward-rotating said date dialadvancement transducer for correction of the calendar during a periodfrom activation to stoppage of said date dial advancement transducer. 9.An electronic timepiece having a calendar advancement device accordingto claim 4, further comprising a control circuit forfast-forward-rotating said date dial advancement transducer forcorrection of the calendar during a period from activation to stoppageof said date dial advancement transducer.
 10. An electronic timepiecehaving a calendar device according to claim 4, wherein abutment of thefeed tooth of the date dial stabilizing Geneva wheel on the teeth ofsaid date dial driving wheel is detected from a signal from a detectionmechanism for detecting start to advance the date dial.
 11. Anelectronic timepiece having a calendar device according to claim 10,wherein the detection mechanism for detecting start to advance the datedial has a pattern provided on the date dial and a photo sensor fordetecting the pattern.
 12. An electronic timepiece having a calendardevice according to claim 10, wherein the detection mechanism fordetecting start to advance the date dial has a load detection circuitfor detecting load on a drive circuit for said date dial advancementtransducer.
 13. An electronic timepiece having a calendar deviceaccording to claim 3, wherein the feed tooth of the date dialstabilizing Geneva wheel is held in a position, when the date dial is ina stabilized state, which is determined according to a ratio betweenforward and backward rotation speeds of said date dial advancementtransducer so that the correcting of the date dial starts after asubstantially same amount of time through either forward or backwardrotation.
 14. An electronic timepiece having a calendar advancementdevice according to claim 3, further comprising a control circuit forfast-forward-rotating said date dial advancement transducer forcorrection of the calendar during a period from activation to stoppageof said date dial advancement transducer.
 15. An electronic timepiecehaving a calendar advancement device according to claim 1, furthercomprising a control circuit for fast-forward-rotating said date dialadvancement transducer for correction of the calendar during a periodfrom activation to stoppage of said date dial advancement transducer.16. An electronic timepiece having a date dial as a rotating indicationpanel for dates on a calendar, comprising: a control device for dates ona calendar, including a date advancement transducer for driving a datedial; a slow-down gear train for transmitting rotation force of saiddate advancement transducer to the date dial; a date dial intermittentrotation drive device constituting a part of said slow-down gear train,for intermittently driving the date dial; and a bounding restraintlever, movable by said intermittent rotation drive device, forrestraining rotation of the date dial in a non-driven state, andreleasing rotation restraint on the date dial in a driven state.
 17. Anelectronic timepiece according to claim 16, wherein said boundingrestraint lever is engaged with teeth of the date dial in a non-drivenstate for rotation restraint, and departs from the teeth of the datedial in a driven state for releasing load due to pressing force appliedto the date dial.
 18. An electronic timepiece having a date dial as arotating indication panel for dates on a calendar, comprising: a controldevice for dates on a calendar, including a date advancement transducerfor driving a date dial; a slow-down gear train for transmittingrotation force of said date advancement transducer to the date dial; abounding restraint lever for restraining rotation of the date dial in anon-driven state, and releasing rotation restraint on the date dial in adriven state, wherein said bounding restraint lever is engaged withteeth of the date dial in a non-driven state for rotation restraint, anddeparts from the teeth of the date dial in a driven state for releasingload due to pressing force applied to the date dial; and a date dialintermittent rotation drive device constituting a part of said slow-downgear train, for intermittently driving the date dial, comprising: a datedial driving wheel arranged to continuously engage with the date dial, adate intermediate wheel having feed teeth for intermittent engagementwith said date dial driving wheel, and an eccentric cam for engagementwith and rotating said bounding restraint lever, wherein said dateintermediate wheel and said eccentric cam have a common rotation center.19. An electronic timepiece according to claim 18, wherein a bearing isprovided between said eccentric cam and said feed teeth, for receivingan axis of said date intermediate wheel.
 20. An electronic timepieceaccording to claim 18, wherein said bounding restraint lever, saideccentric cam, and the teeth of the date dial for engagement with saiddate dial driving wheel are provided on a same planar surface.